Byju's — After cancelling the registration EMI amount was debited

Dear sir,
Last month one of your persons has came to my home and gave demo class for my kid. End of the session she forced us to join in Byjus. I don't have any choice to reject that. Without any option I have join in Byjus and she gave us a study materials to my kid. But later on I was not interested so I have given the cancellation message to byjus. Then 2 days back I have received a message regarding EMI. And I have called to your customer care and explain everything I have said above. They promised me that your person will call me within 24 hours and resolve the problem it seems. But now without my knowledge your company has debited Rs. 4201/- from my account. Is this right approach? How can you do this all these things without my knowledge and without any pre intimation? I need to cancel this and and I need my money refund.. Or else I'll go by legal and file a complaint against Byjus.